Add a day/night cycle.

[dmccoystephenson]

Summary

Add a day/night cycle that periodically dims and brightens the game world by applying a brightness overlay to the rendered game area, affecting all visible entities uniformly.

Background

Roam's renderer draws entities tile-by-tile in Room.drawLocation() (src/world/room.py) and Room.drawWithOffset(), blitting scaled pygame surfaces directly to graphik.gameDisplay. The simplest way to apply a global brightness effect without touching individual entity textures is to blit a semi-transparent black overlay onto the game area rect (Graphik.getGameAreaRect()) after all tiles are drawn each frame, with opacity driven by the current tick and a configurable cycle length. Note: if PR #344 is merged before this, any new print() calls should use getLogger from src/gameLogging/logger.py instead.

Requirements

Config

• Add dayNightCycleEnabled boolean (default true) and dayNightCycleLengthTicks integer (default 43200 — 30 minutes at 30 tps) to config.yml and load both in Config (src/config/config.py)
• Add a Day/Night Cycle toggle button to ConfigScreen (src/screen/configScreen.py), consistent with existing toggles

Cycle Logic

• Create src/world/dayNightCycle.py with a DayNightCycle class registered as a @component in the DI container
• The class should expose a getOverlayOpacity(tick) method that maps the current tick to an opacity value in the range 0 (full brightness, midday) to 200 (near-dark, midnight) using a sine curve so transitions are smooth rather than linear
• Midday should occur at tick % cycleLengthTicks == 0 and midnight at the halfway point

Rendering

• In WorldScreen.draw() (src/screen/worldScreen.py), after all rooms are drawn and before HUD elements, blit a pygame.Surface filled with (0, 0, 0) at the opacity returned by getOverlayOpacity onto the game area rect (graphik.getGameAreaRect())
• Use pygame.SRCALPHA or Surface.set_alpha() for the overlay — do not create a new surface every frame; cache it as a WorldScreen attribute and only recreate it when the game area rect size changes
• The overlay must be clipped to the game area rect so letterbox bars outside the square game area are not affected
• The cycle must be skipped entirely (no overlay drawn) when config.dayNightCycleEnabled is False

Debug Info

• When config.debug is True, include the current cycle phase (e.g. day, dusk, night, dawn) and overlay opacity alongside the existing debug text drawn in WorldScreen

Save/Load

• The cycle derives its state entirely from TickCounter.getTick(), which is already persisted in tick.json — no additional save/load logic is needed

Acceptance Criteria

• The game world smoothly transitions between full brightness (day) and near-darkness (night) on a configurable tick-based cycle
• The overlay is clipped to the game area rect and does not affect letterbox bars
• Toggling dayNightCycleEnabled in the settings screen immediately stops or resumes the overlay
• dayNightCycleLengthTicks in config.yml controls the cycle duration and is respected without a restart
• Debug mode displays the current cycle phase and overlay opacity
• The overlay surface is not reallocated every frame
• All existing tests pass; new tests cover DayNightCycle.getOverlayOpacity() at tick values corresponding to midday, midnight, dusk, and dawn